The answer is D I hope this helps you !
The relative molecular mass of the gas : 64 g/mol
<h3>Further explanation</h3>
Given
Helium rate = 4x an unknown gas
Required
The relative molecular mass of the gas
Solution
Graham's Law

r₁=4 x r₂
r₁ = Helium rate
r₂ = unknown gas rate
M₁= relative molecular mass of Helium = 4 g/mol
M₂ = relative molecular mass of the gas
Input the value :

The answer is C, work. The reaction of the air/gas mixture being ignited produces energy which moves the piston up and down which turns the crankshaft.
You should make a density trap, you get different liquids with different density's ( corn starch , water , alcohol , syrup) and pour them into a big vase and the different density's will sit on top of each other . the best thing to do is to use food coloring so that each level is a different color.
Answer: There are 0.006 moles of acid in the flask.
Explanation:
Given:
= 21.35 mL,
= 0.150 M
= 25.0 mL,
= ?
Formula used to calculate molarity of
is as follows.

Substitute the values into above formula as follows.

As molarity is the number of moles of a substance present in a liter of solution.
Total volume of solution = 
= 21.35 mL + 25.0 mL
= 46.36 mL (1 mL = 0.001 L)
= 0.04636 L
Therefore, moles of acid required are calculated as follows.

Thus, we can conclude that there are 0.006 moles of acid in the flask.